A Chilean police report says van der Sloot initially claimed two robbers surprised him and victim Stephany Flores in their hotel room. He said one of the robbers beat her to death.
"A man came out of the bathroom blocking the access door with a knife in his hand. On the bed was another man with a gun," the Spanish-language report quotes him as saying. "The man with the knife said to be quiet, but Stephany began talking in a loud voice and he hit her in the face, making her nose bleed."
It also says Van der Sloot told Chilean agents that the previous day, he and Flores had been extorted by apparent police officers who demanded $4,000 and a wristwatch he brought from Thailand.
Chilean police told their Peruvian colleagues that the 22-year-old Dutchman responded in English to their questioning but refused to sign a declaration after learning he would be expelled to Peru.
Peruvian police say he confessed to killing Flores after she learned details of the Natalee Holloway case from his laptop.
A Peruvian judge on Friday ordered van der Sloot jailed on charges of first-degree murder and robbery in the killing of a 21-year-old Lima woman, determining that he acted with "ferocity and great cruelty."
If convicted on the murder and robbery charges, Van der Sloot could get 15 to 35 years in prison.
Van der Sloot's newly hired Peruvian attorney, Maximo Altez, has asked the judge to declare his client's confession void on the grounds it was made in the presence of a defense lawyer appointed by police.
Meanwhile, van der Sloot remains the lone suspect in the 2005 disappearance in Aruba of Holloway, and the chief of Peru's criminal police said he told investigators that he knows the location of the U.S. teen's body.
But a Peruvian police official says he didn't know how seriously to take van der Sloot's claims, given his history of dubious statements. The Dutch citizen also said he would only elaborate on the matter before authorities in Aruba.
Van der Sloot was twice arrested in connection with Holloway's disappearance in 2005, but never charged.
The Associated Press contributed to this story.